1. Field of the Invention
The starting point of the invention is a method of operating an arc furnace, particularly for steelmaking, and an arc furnace for carrying out the method.
2. Discussion of Background
Swiss house journal ABB Technik, 10/1992, pp. 3-10, describes a device for the melting-down of scrap, use is there made of a solid graphite electrode in a direct-current arc furnace, in which the furnace cover is movable and the furnace vessel tiltable in order to tip out the slag and the finished melt. If the direct-current arc furnace is used as a reduction furnace for the continuous charging and processing of fine charges, it is fed either through a central opening in the electrode, directly into the arc furnace plasma, or through one or more charging doors next to the electrode. If a premixed fine-grained charge is fed through the hollow electrode, the charging mass flow is controlled so that equilibrium with the arc power can always be maintained. The two-part charging tube has a quick-release coupling and is electrically insulated from a filling hopper of the hollow electrode. The charging apparatus can be swung aside in order to uncouple the bottom part of the charging tube. This furnace has a fixed cover and a stationary shell. The metal and the slag are run off through tap holes at different heights. The furnace transformer is designed to supply the rated power over a wide voltage and current range, so that the arc furnace can be operated at full load. The current supply system must therefore be made sufficiently flexible to enable this optimum to be adjusted in practical operation. As a rule four or five taps are provided on the transformer in order to enable this range to be covered.
Arc furnaces for reduction processes are not tiltable and have a rigidly mounted cover.
In connection with the relevant prior art, reference is also made to EP 0 058 774 B1, from which a tiltable arc furnace having a plurality of solid electrodes for steelmaking is already known, in which loose material is likewise introduced into the arc furnace from a loose-material container via a loose-material conveyor. The loose-material container is here arranged on the loose-material conveyor at a distance from the electrode.
From EP 0 637 634 A1 a method of producing a steel melt in an arc furnace is known, wherein fine-grained solids and/or gases pass through a hollow electrode directly into the arc in order to obtain an arc enclosed in a foamed slag over the flat bath period. In order to form the foamed slag it is also possible for filter dust to be fed in.